1. Field of the Invention
This invention relates to the field of energy-saving and heat-reclaiming devices.
2. Description of the Prior Art
A typical fuel-burning domestic heating system includes a furnace which burns oil, gas, coal, or the like, resulting in the production of hot exhaust gas which passes through a chimney or flue, and a water-heater tank which receives cold water and heats it for delivery to hot water taps throughout the home. Such a system has two major sources of inefficiency: the considerable loss of heat through the chimney, and the tremendous amount of energy used to heat water which, especially in cold months, is initially quite cold.
In the past, heat recovery systems involving a heat exchanger located in a flue to heat water flowing to a water heating system have been proposed, but have met with limited commercial acceptance because of the great expense of such systems compared to the small savings in energy which they produce. Some systems, like that shown in U.S. Pat. No. 4,241,588 to Murphy et al, require complicated valving and a specially adapted flue. Such systems can be costly, and cannot be economically retrofitted to existing flues and water heating systems. Other proposed systems takes up a large amount of space. Often, however, a furnace, is located in a small utility room with little or no space to spare, making such systems useless unless expensive renovation of the utility room and surrounding area is undertaken.
An inherent problem of prior art systems is the attaining of maximum efficiency for the heat exchanger. Some prior art systems involve the use of a single fluid-filled coil. In such an arrangement, exhaust gases flow through the center of the coil without transferring the maximum possible amount of heat to the coil. Thus, heat will still be exhausted out to the environment, and wasted.